The present invention relates generally to engine controllers and, more particularly, to an engine controller for an internal combustion engine which regulates fuel flow to the engine based on engine operational parameters and airflow to the engine.
Internal combustion engines typically include an air-fuel controller that regulates the proportions of air and fuel supplied to one or more combustion chambers of an engine to permit efficient operation thereof while ensuring reduced emissions of undesirable pollutants, such as NOx. One prior art air-fuel controller employs an oxygen probe to measure the content of oxygen present in the-exhaust gas generated by the engine. If the oxygen probe detects high amounts of oxygen in the exhaust, the air-fuel mixture is determined to be too lean and the air-fuel controller increases the proportion of fuel to air in the mixture supplied to the combustion chambers. If the oxygen probe detects low amounts of oxygen in the exhaust, the air-fuel mixture is determined to be too rich and the air-fuel controller reduces the proportion of fuel to air. However, prolonged exposure to engine combustion products and heat often causes the oxygen probe to malfunction.
Quirchmayr et al. U.S. Pat. No. 4,867,127 discloses an air-fuel regulator which regulates an air-fuel mixture supplied through an induction line to an engine. The air-fuel regulator controls the pressure of the air-fuel mixture in the induction line in accordance with the sensed power output of the engine, the sensed mixture pressure and the sensed mixture temperature so that the actual value of the air to fuel ratio follows a desired value curve thereby achieving a reduction in undesirable NOx emissions. The air-fuel mixture pressure is controlled by manipulating a positioning valve disposed in an air bypass line which is coupled across the air-fuel mixer.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.
In accordance with one aspect of the present invention an engine controller for controlling fuel flow supplied to an internal combustion engine by a fuel valve coupled to an air-fuel mixer having an air intake includes a speed sensor and a power sensor. An airflow meter is operatively coupled to the air intake of the air-fuel mixer and a controller unit includes inputs coupled to the speed sensor, the power sensor and the airflow meter and an output coupled to the fuel valve.
In accordance with another aspect of the present invention, a method for controlling fuel flow supplied to an internal combustion engine by an air-fuel mixer includes the steps of sensing an inlet manifold temperature, sensing engine speed, sensing engine output power and sensing airflow supplied to an air-fuel mixer. The method further includes the step of determining desired fuel flow to the air-fuel mixer based on the sensed inlet manifold temperature, the sensed engine speed, the sensed engine output power and the sensed air flow and the step of issuing a drive signal and adjusting fuel flow supplied to the air-fuel mixer to equal substantially a desired fuel flow.
In accordance with yet another aspect of the present invention, an engine having an engine controller for controlling fuel flow supplied to the engine includes an air-fuel mixer coupled to an air source and a fuel source, an inlet manifold in fluid communication with the air-fluid mixer and a combustion chamber in fluid communication with the inlet manifold. A controller unit is responsive to a signal representative of an engine speed, a signal representative of an output power generated by the engine and a signal representative of an actual airflow to the air-fuel mixer, wherein said controller unit develops a drive signal and regulates fuel flow to the air-fuel mixer.